A prime minister has resigned. A relative newcomer to federal politics has shot through Conservative Party ranks to become the heir apparent. The Conservatives' standing in the polls has jumped. Led by Jean Chretien, opposition Liberals who had been sauntering toward a fall election victory have quickened the pace of organizing.

Canada's election-year contest now gives every indication of becoming a classic Conservative-Liberal battle, rather than the multiparty free-for-all many had expected, analysts say.

The "kinder, gentler" social democrats of the New Democratic Party (NDP), led by Audrey McLaughlin, were supposed to surge this year but are fading. The archconservative Alberta-based Reform Party is in trouble, and the Quebec-based separatist Bloc Qucois (BQ) party could be. Both Reform and the BQ seem sure to gain new seats in Parliament, but many votes they might have expected a few months ago will slide instead to Conservatives, analysts say. And NDP voters, many unhappy with NDP governments in Ontar io, British Columbia, and Saskatchewan, may vote Liberal this time.

"In 1935 we had a five-party race, which resulted in Liberals getting a very big majority," says Michael Bliss, a University of Toronto historian. "It's all well and good to talk about political alternatives and new parties between elections. But when it comes to the crunch, most people would like to vote for a candidate whose party has a chance of forming a government."

The turnabout arrived with Prime Minister Brian Mulroney's Feb. 24 resignation announcement. In the weeks since, Defense Minister Kim Campbell has surpassed a field of contenders and appears almost certain to succeed Mr. Mulroney as party leader and prime minister at a June 9-13 party leadership convention.

"She gives them a fighting chance," says Sen. Heath Macquarrie, a "Red Tory" (left-leaning) Conservative, who until Ms. Campbell arose had despaired of a "moderate" leading his party.

Campbell's presence takes "some of the pall" off of Conservatives, concedes Richard Mahoney, president of the Ontario Liberal Party. "Had Mulroney stayed, it would have been almost impossible for us to lose the election."

Polls reveal the shift. A March 18 Gallup poll shows Conservatives, led by Campbell, would collect 29 percent of the vote, a gain of eight percentage points in the month since a similar poll prior to Mulroney's resignation. The Liberals' March lead fell seven points to 42 percent.

The NDP, meanwhile, dropped three points to 13 percent; Reform slipped a point to 7 percent; and the BQ gained five points to 8 percent. "Campbell has changed everything," says Scott Mackay, an Angus Reid pollster. "It's a real race."

Donna Dasko of Environics Research Group, a Toronto polling firm, agrees that Conservatives have surged, but is skeptical the public will forget that Campbell embraced Mulroney policies that many blame for deepening the recession. "It's going to be a tough race for the Conservatives," she says. "It will be difficult to overcome the entire record of the last four years."

In the Liberals' favor is a huge "built-in constituency," says Professor Bliss. Still, insiders in both parties say victory rides on which party woos back the most former constituents from the ranks of Reform, BQ, and NDP.

MULRONEY'S Conservatives won big in Quebec in 1988 and many expect a good fight between Campbell and Lucien Bouchard, the BQ leader. Quebeckers are known to want strong representation in Ottawa. But the BQ - whose mission is to separate Quebec from Canada - will have to convince voters it can deliver government largess to the province in the interim.

Reform leader Preston Manning took aim at a public newly sensitized to the debt problem - of which Canada has more than $600 billion (Canadian, US$480 billion). On March 29, he announced a platform of drastic cuts to unemployment insurance and Old Age Security payments. The move may backfire if it alienates those who backed Reform only because they dislike Mulroney.

Liberal and Conservative insiders agree the economy is the big unknown. Campbell may benefit if the economy improves, while the Liberals will be helped by the status quo.

"The issue for us is to get authorship for the [economic recovery] and be associated with the future," says Hugh Segal, Mulroney's chief of staff. "The prime atmospheric within which we all have to operate is the economy."